A practical diastereoselective synthesis of (−)-bestatin
作者:Suisheng Shang、Andreas V. Willems、Satendra S. Chauhan
DOI:10.1002/psc.3067
日期:2018.3
Diastereoselective addition of nitromethane to Boc‐D‐Phe‐H in the presence of sodium hydride in diethyl ether/hexane containing 15‐crown‐5 and subsequent N,O‐protection with 2,2‐dimethoxypropane gave trans‐oxazolidine in a diastereomeric ratio of >16:1. The oxazolidine was easily separated by column chromatography, which after Nef reaction was coupled to H‐Leu‐OtBu. The 8‐step synthesis afforded (−)‐bestatin
在含有15-crown-5的乙醚/己烷中存在氢化钠的情况下,向Boc - D -Phe-H中非对映选择性地添加硝基甲烷,随后用2,2-二甲氧基丙烷进行N,O-保护,得到非对映体比例的反式-恶唑烷大于16:1。恶唑烷很容易通过柱色谱分离,在Nef反应后,将其偶联到H‐Leu‐O t Bu。经过八步合成后,去保护和离子交换后,(-)-贝他汀的总收率为24.7%。